The present invention relates to a tool for chip removing machining, preferably for parting/grooving, comprising an insert mechanically clampable to a holder. The insert is arranged to be clamped in a slot in the holder by means of a spring-load that arises between the walls of the slot when the insert is pushed into the slot and produces a deflection of one of the slot walls. The invention further relates to an insert to be clamped in the holder.
Such a tool is disclosed in U.S. Pat. No. 4,801,224, the disclosure of which is incorporated by reference herein. That tool 10, depicted herein in FIGS. 1 and 2, comprises a holder 11 and an insert 12. The holder 11 has a rear end, not shown, adapted to be secured to a machine. The free front end of the holder is provided with a slot 13 defined by first and second opposing walls 14, 15 each having a generally V-shaped cross-section. The wall 14 comprises mutually angled planar wall sections 14a, 14b, and the wall 15 comprises mutually angled planar wall sections 15a, 15b. The upper portion of the holder which carries the wall 15 forms an integral cantilever-type clamping arm 16 arranged to clamp the insert between the walls of the slot by means of resilient force when the insert is pushed rearwardly into the slot. The angled wall sections of each wall 14, 15 converge toward the insert to form the V-shape. The wall sections of each wall meet in a rounded-off apex portion and enclose an internal obtuse angle. The front surface of the clamping arm 16 is comprised of a planar abutment surface 17 which determines the final position of the insert 12 in the slot.
The insert 12 is formed of sintered hard metal, such as cemented carbide, especially, tungsten carbide, and comprises a pair of longitudinally extending V-shaped first and second surfaces 21, 22. The first surface 21 extends parallel to the feed direction A of the tool. The second surface 22 comprises mutually inclined front and rear portions 23, 24, which together form an included obtuse angle. The rear portion 24 terminates rearwardly at a location separated from the first surface 21 by a rear face 20. The rear portion 24 converges toward the surface 21 and forms a wedge angle therewith. The surface 21 is configured to slide along the lower wall 14 of the slot, and the portions 23, 24 are configured to slide along the upper wall 15 of the slot. The sides of each surface 21, 22 meet in a central rounded-off portion (see FIG. 2) and form an external obtuse angle which is larger than the internal angle formed between corresponding portions at the holder. Contact occurs between the surface 21 and the wall 14 and between the front portion 23 and the wall 15 at each side of the midline M of the tool (FIG. 2) during the final phase of insertion.
The broader, front part of the insert body is provided with a cutting edge 25 arranged to part or to face a work piece, not shown. Furthermore, the insert is provided with parallel planar side faces 26, 27 and transversely directed front and rear end faces 28, 29. The front portion 23 of the surface 22 is generally parallel to the surface 21 in that it could be exactly parallel or slightly inclined such that it diverges from the surface 21 in a rearward direction.
During insertion of the insert 12 into the slot 16, the rear portion 24 of the surface 22 engages a front end 19 of the clamping arm 16 and elastically deflects the clamping arm away from the opposing portion of the holder. Eventually, the front end 19 engages the front portion 23 of the surface 22 and comes into contact with an abutment surface 30 of the insert. The insert 12 is now frictionally held between the walls 14 and 15 of the slot.
Although this frictional securement is usually adequate, it may occur on occasion that the insert becomes inadvertently dislodged from the holder.
It is, therefore, an object of the invention to increase the frictional forces that secure the insert in the holder.
The objects are achieved by a parting/grooving tool which comprises a holder and an insert removably secured in the holder. The insert includes front and rear ends. The front end contains a cutting edge, and the rear end includes a rear face. Upper and lower surfaces of the insert are of generally V-shaped cross-section and extend along a front-to-rear direction. The V-shape is bisected by a longitudinal midplane of the insert. The holder includes a forwardly opening slot formed by upper and lower front-to-rear extending walls of V-shaped cross-section. Each wall is defined by mutually angled wall sections. The walls face one another and engage the upper and lower surfaces, respectively, of the insert. The walls are elastically flexed apart to frictionally grip the upper and lower surfaces, respectively. At least one of the upper and lower surfaces is provided with recess patterns situated on respective sides of the longitudinal midplane. Each of the recess patterns is configured to define non-recessed portions of the at least one surface, the non-recessed portions being spaced apart along the front-to-rear direction. The wall sections of the holder which engages the at least one surface are planar and frictionally engage the non-recessed portions and extend across the recess patterns.
Preferably, both of the upper and lower surfaces possess the recess pattern and the non-recessed portions.
The invention also pertains to the parting/grooving insert per se.